Operation indicator for airplane engines



Aug. 19, 1527.

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OPERATION INDICATOR FOR AIRPLANE ENGINES Filed Nov. 14, 1944 2Sheets-Sheet l lm'entar wzierjjzwyraafi GROSS iEFEREi'fiCi Aug. 19,1947.

w. H. FITZGERALD, JR; 2,426,089

OPERATION INDICATOR FOR AIRPLANE ENGINES Filed Nov. 14, 1944 2 Sheets-Shet 2 w Inventor Search 5 Paienie'aaug. 19, rear UNITED STATESATENTIOIF'FICE OIERATION INDICATOR FOR AIRPLANE ENGINES Walter H.Fitzgerald, Jr., Carrollton, Tex.

Application November 14, 1944, Serial No. 563,440

ferent positions eccentric to the axis of the resilient liners, due todead weight when the engine -is dead, and torque when the engine isrunning.

Having the foregoing in mind, it is the primary object of my inventionto provide a simple form of device operative electrically under controlof a floating bolt of an airplane engine support to indicate visiblywhether the engine is dead, operating normally and smoothly, or roughly,or very roughly, and which is easy to install, involves few parts, isaccurate, dependable, and inexpensive to manufacture and install.

Other objects, also comprehended by my invention, together with theprecise nature of my improvements, and the advantages thereof, willbecome readily apparent when the succeeding description and claims areread with reference to the drawings accompanying and forming part ofthis specification.

In said drawings:

Figure 1 is a view, partly in vertical section and partly in sideelevation, illustrating my improved operation indicator conditioned toindicate very rough operation of an airplane engine,

Figure 2 is a view in horizontal section taken on the line 2-2 of Figure1,

Figure 3 is a view in vertical section taken on the line 3-3 of Figure1,

Figure 4 is a view similar to Figure 1, but illustrating the indicatorconditioned to indicate that the engine is dead, and

Figure 5 is another view similar to Figure 1, but illustrating theindicator as conditioned to indicate normal smooth operation of theengine.

Referring to the drawings by numerals, I desig 2 Claims. (Cl. 73116)nates a usual type of fixed mount for an airplane engine, not shown, andwhich comprises an annular sleeve 2 provided with a resilient sleevetypeliner 3 therein of rubber, through which one of the engine-securingbolts 4 is extended, normally axially, with its ends fixed in engineparts represented at 5.

According to my invention, an indicator instrument 6, of any of theusual types embodying an electrically operated indicator hand I, isprovided for mounting in any desired manner in a fixed position in theairplane, not shown, the instrument embodying a graduated face dial 8bearing between the graduations 9 thereof the legends Normal, Rough,Out, Very rough, reading from left to right in the order named and withwhich the indicator hand 'I cooperates in the usual manner.

A rod-like feeler finger II] of non-conductive material, with theexception presently noted, is slidably extended, intermediate its ends,through a suitable guide I I in the plane of the support I and with itsfront end portion slidably extended through a suitable radial bore I2 inthe sleeve 2 and another similar bore I3 in the sleeve 3 so that saidfront end of the feeler finger engages one side of the bolt 4. A coiledexpansion spring I surrounding the feeler finger intermediate the guideI I and a fixed collar I5 on said finger urges the feeler finger I0toward the bolt 4 and maintains the front end of said finger in wipingengagement with said bolt.

The rear end of the feeler finger I0 is provided with a laterallyextending contact I8, adapted, when the feeler finger I9 isreciprocated, to wipe over a row of contacts II, I8, I9, 20, suitablymounted in fixed position, and which are grounded through resistances2I, 22, 23, 24, respectively, of successively lower resistance. Theindicator instrument 6 is designed to be connected in circuit with anyone of said resistances by means of a circuit wire 25 leading from oneside of said instrument to one side of a battery 26, the other side ofsaid instrument being connected to ground, as by the wire 21, and theother side of the battery 28 being connected to the contact I6 by acircuit Wire 28. The resistances 2|, 22, 23, 26, when connected incircuit with the instrument 3, are arranged to control the indicatorhand I to indicate the legends Normal, ough, Out, and Very rough,respectively.

Referring now to the operation of the invention. When the engine isdead, the bolt 4 assumes a downward, eccentric position in verticalalignment with the axis of the sleeves 2, 3, as shown in Figure 4; thespring I4 thrusts the feeler finger IS! forwardly against said bolt sothat the contact I6 is advanced into engagement with the contact I 9,thus completing a circuit through the resistance 23 to ground. Thiscauses the indicator hand I to swing into a position opposite the legendOut, thus indicating that the engine is dead. The circuit thus closedmay be traced through the ground wire 21 to one side of the instrument6, over circuit wire 25 from the other side of said instrument to thebattery 26, and from the battery to the contact IE, then through contactl9 and resistance 23 to ground. When the engine is operating normally,and smoothly, the bolt d is swung clockwise into an eccentric positionrelative to the axis of the sleeves 2', 3, as shown in Figure 5, underthe torque created by operation and other factors. In this position ofthe bolt 4, the spring Id thrusts the feeler finger l forwardlysuifi'ciently to engage the contact IS with the contact l1, thus.closing the circuit through the instrument 6 with the resistance 2|interposed in the circuit and causing the indicator hand to swing into aposi tion opposite Normal. When the engine is operating roughly,slightly the bolt 4 vibrates about a mean position somewhere betweenNormal and Out positions and under such vibration moves eccentrically ofthe axis of the sleeves 2. 3--counter-clockwise from vertical alignmentwith said axis, thus thrustin the feeler finger l8 rearwardly inopposition to the spring 14 to engage the contact 16 with the contact 18and close the circuit with the resistance 22. interposed therein, thuscausing the indicator hand T to assume a position opposite the legend.

Rough. When the engine is operatingvery roughly, the bolt 4 vibratesthrough a Wider range from said mean position and as a result of greateramplitude Of vibration moves further counter-clockwise, as shown in.Figure I, thrusting the feeler finger 18 further rearwardly to engagecontact #6 with the contact 21'] at one end of the range of vibration ofsaid bolt and thereby close the circuit with the resistance 24interposed therein, thus causing the indicator hand T to swing into aposition opposite the legend Very' rough-1y, Of course, when the engineis operating roughly, as a result of greater amplitude of vibration ofthe bolt 4, the contact 15 will Wipingly engage, momentarily, thecontact 19, causing said hand I to indicate Out at the opposite end ofthe range of vibration of saidbolt. However, when said hand 1 vibratesover Out and Very rough on the face dial 8, the indication Out may bedisregarded and the indication Very rough considered solely assignifying the running condition of the engine.

The foregoing will, it is believed, sufiice to impart a clearunderstanding of my invention without further explanation.

Manifestly, the invention, as described, is susceptible of modificationwithout departing from the inventive concept, and right is hereinreserved to such modifications as fall within the scope of the appendedclaims.

What I' claim is: a

position and rough operation of the engine causes the bolt to vibrateover a range of positions dependent up on the degree of roughness, aninstrument for indicating the nature of the engine operation or itsnon-operation, and means for actuating said instrument in response tomovement of said bolt comprising an electric circuit, resistances ofdifferent values, and a feeler finger for selectively interposing saidresistances in the circuit slidably mounted and spring pressed to engageand follow said bolt.

2. In combination with a floating mounting of an engine including aresilient bushing carried by a fixed mounting element and through whichan engine securing bolt extends, said engine be- 5 ing so mounted thatwhen the same is not operating the dead Weight thereof causes the boltto assume one position within the resilient bushing, the torque of theengine when operating normally causes the bolt to assume a differentposition and rough operation of the engine causes the bolt tovibrateover a range of positions dependent upon the degree of roughness, aninstrument for indicating the nature of the engine operation or itsnon-operation, and means for actuating said instrument in response tomovement of said bolt comprising an electric circuit, resistances ofdifferent values, and a feeler finger for selectively interposing saidresistances in the circuit slidably mounted and spring pressed to engageand follow said bolt, said feeler finger slidably extending through saidfixed mountin element and into said bushing to said bolt.

WALTER H. FITZGERALD, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,095,142 Lurenbaum Oct. 5, 1937996,170 Vannatter June 27, 1911 2,167,533 Solomon July 25, 19391,057,261 Norton Mar. 25, 1913 2,248,653 Allendorfi Jan. 27, 1939FOREIGN PATENTS Number Country Date 145,371 Austria Apr. 25, 1936500,247 Great Britain Feb. 6, 1939

